Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.5 (thrombin)
33,306 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Proliferation of vascular smooth muscle cells (VSMCs) is postulated to be one of the key events in the pathogenesis of atherosclerosis and restenosis. We investigated whether YD-3, a lowmolecular weight, non-peptide compound, could modulate proliferation of VSMCs in vitro and restenosis after balloon angioplasty in vivo. We examined the effect of YD-3 on thrombininduced VSMC proliferation by [(3)H]thymidine incorporation assay. The data demonstrated that YD-3 inhibited VSMC proliferation in a concentration-dependent manner. To define the mechanisms of YD-3 action, we found that YD-3 showed a profound inhibition on thrombin-induced Ras and ERK1/2 activities by using Western blotting analysis. Furthermore, oral administration of YD-3 exhibited a marked reduction in neointimal thickness using the carotid injury model in rats. Using immunochemical detection, our experiments also revealed that YD-3 significantly suppressed expression of the PAR-1 receptor, and markedly inhibited PAR-1-activating peptide (SFLLRN)-induced VSMC proliferation in a concentration-dependent manner. These results suggest that YD-3 inhibits thrombin-induced VSMC growth via the Ras- and ERK1/2-mediated signaling pathway. Moreover, YD-3 also shows a developmental potential in the treatment of atherosclerosis and restenosis after vascular injury.
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PMID:The indazole derivative YD-3 inhibits thrombin-induced vascular smooth muscle cell proliferation and attenuates intimal thickening after balloon injury. 1558 28

Using adenoviruses encoding RGS2, RGS4 and Lsc (regulator of G protein signalling (RGS) domain of p115 RhoGEF), we investigated the contributions of G(q/11), Gi and G(12/13) proteins to G protein-coupled receptor (GPCR)-mediated activation of the extracellular signal-regulated kinase (ERK) pathway in adult rat ventricular myocytes (ARVM). Exposure to phenylephrine, endothelin-1 (ET-1) or thrombin induced significant activation of ERK1/2 and their downstream target 90 kDa ribosomal S6 kinase (p90RSK), which was abolished by overexpression of RGS4 (inhibits signalling via G(q/11) and Gi) or RGS2 (inhibits signalling via G(q/11)). Pertussis toxin (inhibits signalling via Gi) only partially attenuated the activation of ERK1/2 and p90(RSK) by phenylephrine and ET-1, but abolished such activation by thrombin. Overexpression of Lsc (inhibits signalling via G(12/13)) did not affect the responses to phenylephrine and ET-1, but suppressed the activation of ERK1/2 and p90RSK by thrombin. We conclude that full activation of the ERK pathway in ARVM by alpha1-adrenergic, ET-1 and thrombin receptors requires the activation of distinct families of heterotrimeric G proteins.
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PMID:Regulation of the extracellular signal-regulated kinase pathway in adult myocardium: differential roles of G(q/11), Gi and G(12/13) proteins in signalling by alpha1-adrenergic, endothelin-1 and thrombin-sensitive protease-activated receptors. 1568 40

The activation and function of c-Jun N-terminal kinases (JNKs) were investigated in primary microglia cultures from neonatal rat brain, which express all three JNK isoforms. Lipopolysaccharide (LPS), tumor necrosis factor-alpha (TNF-alpha), and thrombin preparations induced a rapid and lasting activation of JNKs in the cytoplasm. In the nucleus, the activation patterns were rather complex. In untreated microglia, the small pool of nuclear JNKs was strongly activated, while the high-affinity JNK substrate c-Jun was only weakly phosphorylated. Stimulation with LPS increased the total amount of nuclear JNKs and the phosphorylation of the transcription factor c-Jun. Levels of activated JNKs in the nucleus, however, rapidly decreased. Analysis of the nuclear JNK isoforms revealed that the amount of JNK1 declined, while JNK2 increased, and the weakly expressed JNK3 did not vary. This observation suggests that JNK2 is mainly responsible for the activation of c-Jun in this context. Upstream of JNKs, LPS induced a lasting activation of the constitutively present JNK kinase MKK4. The function of JNKs in LPS-triggered cellular reactions was investigated using SP600125 (0.5-5 microM), a direct inhibitor of JNKs. Inhibition of JNKs reduced the LPS-induced metabolic activity and induction of the AP-1 target genes cyclooxygenase-2 (Cox-2), TNF-alpha, monocyte chemoattractant protein-1 (MCP-1), and interleukin-6 (IL-6) in response to LPS, while ERK1/2 and p38 alpha had a more pronounced effect on LPS-induced cellular enlargement than JNKs. In summary, JNKs are essential mediators of relevant pro-inflammatory functions in microglia with different contributions of the JNK isoforms.
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PMID:c-Jun N-terminal kinases (JNKs) mediate pro-inflammatory actions of microglia. 1573 88

This study evaluated the role of thrombin-activated microglia in the neurodegeneration of mesencephalic cultures. Immunocytochemical and biochemical evidence indicated that in co-cultures consisting of rat cortical microglia and mesencephalic neurons, thrombin led to nonselective loss of mesencephalic neurons. Accompanying neurodegeneration, microglial activation was obvious, evidenced by expression of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-1beta, inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) and by increasing production of TNF-alpha and nitric oxide (NO). In mesencephalic neurons treated with conditioned media (CM) taken from thrombin-activated microglia, the number of dopaminergic neurons was significantly attenuated. The neurotoxicity of the CM was diminished when it was derived from microglia co-treated with thrombin and either an extracellular signal-regulated kinase 1/2 (ERK1/2) pathway inhibitor (PD98059) or a p38-mitogen-activated protein kinase (p38-MAPK) inhibitor (SB203580). Moreover, jun N-terminal kinase (JNK) and p38-MAPK were activated in mesencephalic neurons treated with CM of thrombin-activated microglia. Inhibition of JNK and p38-MAPK rescued the dopaminergic neurons. Collectively, these results indicate that thrombin-activated microglia induce neurodegeneration in cultured mesencephalic neurons and that the MAPKs actively participate in both microglial activation and neurodegeneration. The present data carefully suggest that microglial activation triggered by thrombin may be involved in the neuropathological processes of dopaminergic neuronal cell death that occur in Parkinson's disease.
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PMID:Thrombin-activated microglia contribute to death of dopaminergic neurons in rat mesencephalic cultures: dual roles of mitogen-activated protein kinase signaling pathways. 1578 35

The p21-activated serine/threonine kinases (PAK) play an important role in a variety of cellular functions. However, their role in the smooth muscle response to thrombin, which is activated upon vascular injury and promotes vascular remodelling processes, is not resolved. Here we investigated the role of PAK in thrombin signalling and regulation of tissue factor (TF), the activator of the extrinsic coagulation cascade, in pulmonary artery smooth muscle cells (PASMC), the main cell type responsible for vascular remodelling in pulmonary hypertension. PAK was rapidly phosphorylated in response to thrombin. Thrombin and active PAKT423E phosphorylated p38 MAP kinase (p38MAPK), ERK1/2, phosphatidylinositol-dependent kinase-1 (PDK1) and protein kinase B/Akt (PKB) whereas kinase-deficient PAK1 prevented activation of these kinases by thrombin. In addition, kinase- deficient MKK3 inhibited activation of PDK1 and PKB by thrombin. Further, thrombin and active PAK1 induced TF expression and promoter activity while kinase-deficient PAK1 diminished thrombin-induced TF upregulation. Moreover, kinase-deficient MKK3, PDK1 and PKB inhibited thrombin- and PAK-dependent TF expression and promoter activity. Together these findings show that PAK is a critical element of thrombin signalling in PASMC which is involved in the regulation of TF expression by sequentially activating MKK3/p38MAPK, PDK1 and PKB. Thus, PAK may play an important role in promoting vascular remodelling processes in pulmonary hypertension.
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PMID:Thrombin activates the p21-activated kinase in pulmonary artery smooth muscle cells. Role in tissue factor expression. 1596 4

We have previously reported that protease-activated receptor 1 (PAR1 or thrombin receptor) is over-expressed in metastatic prostate cancer cell lines compared to prostate epithelial cells. In this study, we examined 1,074 prostate biopsies by tissue microarray analysis and demonstrated that PAR1 expression is significantly increased in prostate cancer compared to normal prostate epithelial cells and benign prostatic hyperplasia. We hypothesized that PAR1 activation contributed to prostate cancer cell progression. We demonstrated that stimulation of PAR1 by thrombin or thrombin receptor activating peptide (TRAP6), in androgen-independent DU145 and PC-3 cells resulted in increased DNA binding activity of the NFkappaB p65 subunit. IL-6 and IL-8 levels were also elevated in conditioned media by at least two-fold within 4-6 h of PAR1 activation. This induction of cytokine production was abrogated by pretreatment of cells with the NFkappaB inhibitor caffeic acid phorbol ester. The p38 and ERK1/2 MAPK signaling cascades were also activated by PAR1 stimulation, whereas the SAPK/JNK pathway was unaffected. Inhibition of p38 and ERK1/2 by SB-203589 and PD-098059, respectively, did not abrogate NFkappaB activity, suggesting an independent induction of NFkappaB by PAR1 stimulation. Furthermore, TUNEL assay showed that activation of PAR1 attenuated docetaxel induced apoptosis through the upregulation of the Bcl-2 family protein Bcl-xL. Akt activation was not observed, suggesting that drug resistance induced by PAR1 was independent of PI3K signaling pathway. Because thrombin and PAR1 are over-expressed in prostate cancer patients, targeting the inhibition of their interaction may attenuate NFkappaB signaling transduction resulting in decreased drug resistance and subsequent survival of prostate cancer cells.
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PMID:PAR1-mediated NFkappaB activation promotes survival of prostate cancer cells through a Bcl-xL-dependent mechanism. 1605 12

Thrombin, an important mediator of thrombosis and inflammation, may also enhance vascular cytoprotection. Thus thrombin induces expression of the complement-inhibitory protein decay-accelerating factor (DAF) in human umbilical vein endothelial cells (HUVECs), thus increasing protection against complement-mediated injury. Using PKC isozyme-specific peptide antagonists and adenoviral constructs, we have shown in the present study that PKC-epsilon is the primary isozyme involved in DAF induction by thrombin. Experiments with proteinase-activated receptor-1 (PAR1) and PAR2 activating peptides (APs) showed that DAF expression induced by PAR1-AP was PKC-alpha-dependent; in contrast, PAR2-AP induction of DAF required activation of PKC-epsilon. PAR1-AP and PAR2-AP in combination exerted an additive effect on DAF protein expression, which was equivalent to that observed with thrombin alone. These data implied a specific role for PAR2 in DAF induction, which was supported by the observation that upregulation of endothelial cell (EC) PAR2-enhanced DAF induction by thrombin. ERK1/2, p38, and JNK MAPK were also involved in thrombin-induced DAF upregulation, with evidence of interdependence between ERK1/2 and JNK. A role for transactivation of PAR2 by PAR1 was suggested by partial inhibition of thrombin-induced DAF expression by the PAR1 signaling antagonists BMS-200261 and SCH79797, whereas inhibition of thrombin-induced cleavage of PAR1 by specific MAbs or hirudin completely abrogated the response. Together, these data imply that the predominant pathway for thrombin-induced DAF expression involves transactivation of PAR2 by PAR1 and signaling via PKC-epsilon/MAPK. This may represent an important, novel pathway for endothelial cytoprotection during inflammation and angiogenesis and suggests that PAR2 may play a central role in some thrombin-induced responses.
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PMID:A role for proteinase-activated receptor 2 and PKC-epsilon in thrombin-mediated induction of decay-accelerating factor on human endothelial cells. 1607 88

Matrix metalloproteinases (MMPs) play key roles in vascular remodeling. We characterized the role of inflammatory mediators and extracellular signal-regulated kinases (ERKs) in the control of arterialized vein graft expression of MMP-9, MMP-2, and membrane-type 1-MMP (MT1-MMP) and of the tissue inhibitor of metalloproteinases-2 (TIMP-2). For this purpose we used a canine model of jugular vein to carotid artery interposition graft and analyzed the vein grafts at various postoperative times (30 min to 28 days) using the contralateral vein as a control. To study the role of ERK-1/2, veins were incubated with the mitogen-activated protein kinase kinase (MEK-1/2) inhibitor UO126 for 30 min before being grafted. Vein graft extracts were analyzed for MMPs, TIMP-2, tumor necrosis factor-alpha (TNF-alpha), polymorphonuclear neutrophil (PMN) infiltration, myeloperoxidase (MPO), and thrombin activity, and for ERK-1/2 activation. Vein graft arterialization resulted in rapid and sustained (8 h to 28 days) upregulation of vein graft-associated MMP-9, MMP-2, MT1-MMP, thrombin activity, and TNF-alpha levels with concomitant TIMP-2 downregulation. MMP-2 activation preceded MT1-MMP upregulation. PMN infiltration and vein graft-associated MPO activity increased within hours after arterialization, indicating a prompt, local inflammatory response. In cultured smooth muscle cells, both thrombin and TNF-alpha upregulated MT1-MMP expression; however, only thrombin activated MMP-2. Inhibition of ERK-1/2 activation blocked arterialization-induced upregulation of MMP-2, MMP-9, and MT1-MMP. Thus, thrombin, inflammatory mediators, and activation of the ERK-1/2 pathway control MMP and TIMP-2 expression in arterialized vein grafts.
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PMID:Matrix metalloproteinase expression in vein grafts: role of inflammatory mediators and extracellular signal-regulated kinases-1 and -2. 1628 40

1.--Thrombin is activated during gingival tissue injury and inflammation. Thrombin (platelet)-rich plasma has been used for periodontal regeneration with success. Thrombin and other bacterial proteases also affect the functions of adjacent periodontal cells via stimulation of protease-activated receptors (PARs). 2.--We noted that thrombin (0.1-2 U ml(-1)), human, and frog PAR-1 agonist peptide (20-240 microM) induced the gingival fibroblast (GF)-populated collagen gel contraction within 2 h of exposure. However, PAR-2, PAR-3, and PAR-4 agonist peptide (20-240 microM) showed little effect on collagen gel contraction. U73122 (phospholipase C inhibitor) and 2-APB (IP3 antagonist) were effective in inhibition of GF contraction. 3.--Thrombin-induced GF contraction was inhibited by 5 mM EGTA (an extracellular calcium chelator) and verapamil (an L-type calcium channel blocker). In addition, W7 (10 and 25 microM, a calcium/calmodulin (CaM) inhibitor), ML-7 (50 microM, myosin light chain kinase (MLCK) inhibitor), and HA1077 (100 microM, Rho kinase inhibitor) completely inhibited the thrombin-induced collagen gel contraction. Thrombin also induced the phosphorylation of ERK1/ERK2 and elevated the Rho-GTP levels in GF. 4.--However, U0126 only partially inhibited the thrombin-induced GF contraction. Similarly, wortmannin (100 nM), LY294002 (20 microM) (two PI3K inhibitor) and genistein also showed partial inhibition. Moreover, NAC was not able to suppress the GF contraction, as supported by the slight decrease in reactive oxygen species production in GF by thrombin. 5.--Thrombin also stimulated metalloproteinase-2 (MMP-2) and MMP-3 production in GF. But addition of GM6001 or 1,10-phenanthroline, two MMP inhibitors, could not inhibit the thrombin-induced GF contraction. 6.--These results indicate that thrombin is crucial in the periodontal inflammation and wound healing by promoting GF contraction. This event is mainly mediated via PAR-1 activation, PLC activation, extracellular calcium influx via L-type calcium channel, and the calcium/CaM-MLCK and Rho kinase activation pathway.
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PMID:Signaling mechanism of thrombin-induced gingival fibroblast-populated collagen gel contraction. 1629 51

The functional significance of protease-activated receptors (PARs) in endothelial cells is largely undefined, and the intracellular consequences of their activation are poorly understood. Here, we show that the serine protease thrombin, a PAR-1-selective peptide (TFLLRN), and SLIGKV (PAR-2-selective peptide) induce cyclooxygenase-2 (COX-2) protein and mRNA expression in human endothelial cells without modifying COX-1 expression. COX-2 induction was accompanied by sustained production of 6-keto-PGF1alpha, the stable hydrolysis product of prostacyclin, and this was inhibited by indomethacin and the COX-2-selective inhibitor NS398. PAR-1 and PAR-2 stimulation rapidly activated both ERK1/2 and p38MAPK, and pharmacological blockade of MEK with either PD98059 or U0126 or of p38MAPK by SB203580 or SB202190 strongly inhibited thrombin- and SLIGKV-induced COX-2 expression and 6-keto-PGF1alpha formation. Thrombin and peptide agonists of PAR-1 and PAR-2 increased luciferase activity in human umbilical vein endothelial cells infected with an NF-kappaB-dependent luciferase reporter adenovirus, and this, as well as PAR-induced 6-keto-PGF1alpha synthesis, was inhibited by co-infection with adenovirus encoding wild-type or mutated (Y42F) IkappaBalpha. Thrombin- and SLIGKV-induced COX-2 expression and 6-keto-PGF1alpha generation were markedly attenuated by the NF-kappaB inhibitor PG490 and partially inhibited by the proteasome pathway inhibitor MG-132. Activation of PAR-1 or PAR-2 promoted nuclear translocation and phosphorylation of p65-NF-kappaB, and thrombin-induced but not PAR-2-induced p65-NF-kappaB phosphorylation was reduced by inhibition of MEK or p38MAPK. Activation of PAR-4 by AYPGKF increased phosphorylation of ERK1/2 and p38MAPK without modifying NF-kappaB activation or COX-2 induction. Our data show that PAR-1 and PAR-2, but not PAR-4, are coupled with COX-2 expression and sustained endothelial production of vasculoprotective prostacyclin by mechanisms that depend on ERK1/2, p38MAPK, and IkappaBalpha-dependent NF-kappaB activation.
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PMID:Cyclooxygenase-2 induction and prostacyclin release by protease-activated receptors in endothelial cells require cooperation between mitogen-activated protein kinase and NF-kappaB pathways. 1646 9


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